Water-disintegrable material and device for assaying a body fluid

ABSTRACT

A water-disintegrable support paper material largely formed of fibrous carboxymethylcellulose or carboxyethylcellulose having a degree of etherification of 0.1 to 1.0 and a degree of base saturation of 20% or more. A solution or dispersion of that paper has a pH of 5.0 to 8.0. There is also disclosed a composition for forming a water-disintegrable coat for coating on the support, the composition being a mixture of (a) at least one water-insoluble resin capable of forming a film having a saturation hygroscopicity less than 15% at a 90% relative humidity, (b) at least one water-soluble resin capable of forming film having a saturation hygroscopicity of 15% or more at a 90% relative humidity, and (c) a solvent in which both the resins (a) and (b) can dissolve. Lastly, there is disclosed a device for assaying a body fluid obtained by providing a body fluid assay reagent layer on at least a part of the coat on the support material, giving the device improved maneuverability and toughness during inspection and improved disintegrability after use.

TECHNICAL FIELD

The present invention concerns a water-disintegrable material and itsuse. More specifically, this invention relates to a material which canbe disintegrated (solubilized or swelled) by water to such an extentthat it can be allowed to flow in water, although it retains a completecoat form for a certain short time in water. For instance, this materialmay be used as formats for confidential papers, frames for raising riceseedlings, seeding sheets, seedling sheets, water-soluble waterabsorption paper, materials for body fluid assay devices or kits, and soon. Before or during use, that material plays a recording medium,delivery, protection or other role while keeping its original form and,after that, it is eventually allowed to be dissolved and dispersed inwater for disposal.

BACKGROUND ART

Water-soluble and -swelling resin coats designed to flow in water aremade of such resins as polyvinyl alcohol, polyvinyl pyrrolidone andviscose with the aid of coating agents.

The aforesaid resin coats made of water-soluble resins by and large aresatisfactory in terms of being capable of being allowed to flow inwater.

However, in some applications where resin coats are required to retaintheir film forms stably in water for an initial certain short timewithout being swollen on their surfaces, there are diverse demandstoward their minimum non-swelling time in water, depending upon whatthey are used for. Moreover, there are different requirements for howmuch soluble or swollen resin coats should be in water so as to beeventually allowed to flow in water, for instance, between industrialwaste water disposal and life-related waste water disposal. A great dealof difficulty is thus involved in forming resin coats meeting suchdifferent requirements of a single resin.

For instance, water-soluble and-dispersible fibrous materials used asthe supports of body fluid assay kits or devices are required to retaintheir resin coats stably in water for a certain, if not long, period oftime. Yet it is very difficult to form a resin coat meeting such arequirement in a simple manner.

Until now, the supports for the aforesaid body fluid assay kits havebeen made of plastic sheets such as polystyrene sheets, because theyshould have a suitable degree of rigidity. However, such plastic sheetsupports cannot be disposed of in toilet facilities after use, sincethey are neither soluble nor dispersible in water. Thus, it is anuisance for the users to throw away them hygienically after use.

For that reason, body fluid assay devices comprising a test piece sheetof such water-soluble resins as polyvinyl alcohol and polyvinylpyrrolidone (Japanese Patent Kokai Publication No. 62-24145) or asupport obtained by making use of paper obtained by processing a fibrouscomponent comprising pulp or regenerated pulp and a binder componentcomprising such a water-soluble resin as carboxymethylcellulose(Japanese Patent Laid-Open Publication No. 60-238763) by thepaper-making technique have been proposed as toilet-disposable,water-dispersible body fluid assay devices.

In the first-mentioned body fluid assay device in which the support ismade of a water-soluble resin, it is required that a plurality of filmsof the aforesaid water-soluble resin be laminated together in order forthat support to retain the sufficient rigidity required for that bodyfluid assay device. This body fluid assay device is not only troublesometo assemble, but a time as long as 30 minutes or more is also needed forit to dissolve and disperse in water, when it has a thickness sufficientto achieve the aforesaid rigidity.

On the other hand, the second-mentioned body fluid assay device, whosesupport is made of paper obtained by the paper-making process using afibrous component comprising pulp or regenerated pulp and a bindercomponent of such a water-soluble resin as carboxymethylcellulose, iseasy to handle because, once used, it can be disposed of in toiletfacilities. A problem with this device, however, is that when thesupport is to be coated as by printing with an assay reagent layer,optionally with the reference color layer for determination, printingink is likely to penetrate through the support. This makes it difficultto coat on the support the desired assay reagent layer optionally withthe reference color layer for determination.

Some additional versions of body fluid assay devices have been proposedin Japanese Patent Laid-Open Publication Nos. 60-238763 and 1-121752,which include a support obtained by coating or laminating awater-soluble resin on either or both sides of paper prepared by thepaper-making process using a fibrous component comprising pulp orregenerated pulp and a binder component of such a water-soluble resin ascarboxymethylcellulose. These are said to retain shape during use and bedisposable in toilet facilities.

However, the inventors' finding teaches that when a body fluid assaydevice making use of this support is immersed in a body fluid sampleover too long a period of time, it cannot retain shape and tends to dropin terms of post-immersion rigidity. Thus, that body fluid assay deviceis less than satisfactory in terms of shape retention, since it sags atits end within the time of about 60 seconds required for coloration.Especially when a urine sample is injected directly onto the its reagentcarrying region, its support is apt to suffer damage and so is less thansatisfactory.

DISCLOSURE OF THE INVENTION

The present invention provides a body fluid assay device, wherein (a)while the support region possesses rigidity sufficient to serve as asupport therefor, (b) it is so well dispersible or soluble in water thatthe assay unit can be flushed down the toilet (c) a given assay reagentlayer together with a control reference color layer is orderly appliedon the support's surface by coating without causing penetration ofprinting ink therethrough, and (d) an increased adhesion strength isobtained between the support and the coat layer providing the assayreagent layer, and (e) the device possesses such toughness as to enablea fluid body sample to be injected from a syringe onto the reagentlayer, i.e. such toughness as to a sample, e.g. a urine sample to beinspected by injecting it onto the reagent layer, not via a separatevessel such as a cup, and a material therefor.

The water-disintegrable support material according to this inventioncomprises paper composed mainly of fibrous carboxymethylcellulose orcarboxyethylcellulose having an etherification degree of 0.1 to 1.0 andprepared by the paper-making process, and characterized in that thefibrous carboxymethylcellulose or carboxyethylcellulose forming a majorpart of said support material has a degree of base saturation of 20% ormore and a solution or dispersion of said paper is in the pH range of5.0 to 8.0.

A composition for forming a water-disintegrable film, which is to becoated on the aforesaid support according to this invention, ischaracterized by comprising a mixture of (a) at least onewater-insoluble resin capable of forming a film having a saturationhygroscopicity less than 15% at a 90% relative humidity with (b) atleast one water-soluble resin capable of forming a film having asaturation hygroscopicity of 15% or higher at a 90% relative humidity,and (c) a solvent in which said resins (a) and (b) can dissolve.

The water-disintegrable substrate according to this invention isobtained by forming a coat layer comprising the aforesaid composition onthe aforesaid support. It is understood that the coating layer or layersmay be coated or otherwise laminated on either or both sides of thesupport.

A device for assaying a body fluid may be obtained by forming a bodyfluid assay reagent layer on at least a part of the aforesaid coatinglayer(s) of the substrate.

BEST MODE FOR CARRYING OUT THE INVENTION

In what follows, the present invention will be explained moreillustratively with reference to the components used for the preparationof the body fluid assay device.

It is to be understood that while the body fluid assay unit according tothis invention may take various forms such as sheets and strips, thepresent invention will now be described with reference to the strip typeof body fluid assay device.

For the purpose of detecting, diagnosing and treating various diseases,examination is often made of whether or not such body fluids as urine,blood and lymph contain such ingredients as glucose and protein, theircontent and pH, and so on. Used to this end are body fluid assay stripsin which the supports carry various assay reagent layers, optionallywith reference color layers for determination.

For the water-soluble and-dispersible, fibrous supports of body fluidassay strips, use may be made of, e.g.:

1) paper made by the paper-making process in which reclaimed pulp orpulp is formed into paper using such a water-soluble resin ascarboxymethylcellulose as a binder;

2) paper obtained by the paper-making process from papermaking materialsin which the major fibrous component is fibrous carboxymethylcelluloseor carboxyethylcellulose having a degree of etherification in the rangeof 0.1 to 1.0; and

3) paper made by the paper-making process, in which the major fibrouscomponent or the aforesaid fibrous carboxymethylcellulose orcarboxyethylcellulose is regulated to 20% or more in terms of the degreeof base saturation, and which provides a solution or dispersion with itspH lying in the range of 5.0 to 8.0.

Of the above-mentioned paper materials, the greatest preference is givento the paper (3) composed mainly of fibers, in which the fibrouscarboxymethylcellulose or carboxyethylcellulose is adjusted to a degreeof base saturation of 20% or more and which provides a solution ordispersion with its pH lying in the range of 5.0 to 8.0. This is becausethe best results of examination are obtained since the pH of the sampleto be inspected with the body fluid assay strip is not affected by thesupport itself.

For instance, the detection of glucose in body fluids makes use of thereaction of the glucose with atmospheric oxygen under the action ofglucose oxidase or other oxidase, by which it is eventually oxidizedinto gluconic acid and hydrogen peroxide. The thus formed hydrogenperoxide produces nascent oxygen under the action of peroxidase. Then,this oxygen is allowed to react with an indicator to be oxidized such asguaiac fat or o-tolidine. Whether or not the glucose is found or itsquantity is determined by the degree of color of the indicator.

For the detection of glucose based on this reaction, the indicatorcarried on a support is usually adjusted to such an acidic pH as toeffect a preferable color change in a reagent layer for detectingglucose.

The detection of protein in body fluids relies upon the principles,according to which as a protein detecting indicator whose pH ismaintained on an acidic side, such as Tetrabromophenol Blue,Tetrabromothymol Blue or tetraphthalein ether ester forms a complex withthe protein contained in body fluids, it turns from acidic yellow tobasic blue. The quantity of protein in body fluids is determined by howdiscolored that indicator is.

Thus, the protein detecting reagent layer carried on a support must bemaintained on an acidic pH side at an initial stage of the reaction.

The detection of urobilinogen in body fluids is based on the principles,according to which as that urobilinogen reacts a complex withp-di(alkyl)aminobenzaldehyde to form a complex, it shows an yellowishpink to reddish purple color depending upon what concentration thaturobilinogen is in. The urobilinogen detecting reagent layer carried ona support must again be maintained on an acidic pH side in an earlystage of the reaction.

When detection is carried out with a body fluid assay strip comprising asupport and a reagent layer carried thereon, it is not that only thereagent layer comes into contact with the body fluids to be tested. Inother words, that reagent layer with the support is brought into contactwith the body fluids. Hence, if the pH of the body fluids is likely tochange by contact with the support, then it would mislead the obtainedresults of inspection.

According to the body fluid assay strip of this invention, the paperpreferably used as its support is composed mainly of fibrouscarboxymethylcellulose and/or fibrous carboxyethylcellulose which have adegree of etherification lying in the range of 0.1 to 1.0.Alternatively, the fibrous carboxymethylcellulose orcarboxyethylcellulose having a degree of etherification lying in therange of 0.1 to 1.0 may be mixed with other paper-making fibrouscomponents such as paper-making kraft pulp or sulfite pulp, rayon pulp,polyamide fibers and polyester fibers.

In the case of the latter paper obtained from mixed fibers, however, itis preferred that the other fibrous components be used in an amount of50 parts by weight or less per 100 parts by weight of theabove-mentioned carboxymethylcellulose plus carboxyethylcellulosecomponents. This is because in an amount exceeding 50 parts by weight,the resulting paper tends to degrade in its dispersibility in water.

It is also required that the degrees of etherification of thecarboxymethylcellulose and carboxyethylcellulose forming a major part ofthe paper be 0.1 or more, because at below 0.1 the resulting paperbecomes less than satisfactory in terms of its water dispersibility andsolubility. In this connection, it is noted that when thecarboxymethylcellulose and carboxylethylcellulose have a degree ofetherification of 0.65 or more, the fibers swell so vigorously thatpapermaking is troublesome. However, if no weight is attached to thepaper-making speed, it is then possible to make use of material having adegree of etherification of at most 1.0.

However, preference is usually given to using fibrouscarboxymethylcellulose or carboxylethylcellulose having a degree ofetherification of 0.40 to 0.60 in view of paper-making considerations aswell as the water dispersibility and solubility and strength of theresulting paper.

In the paper forming part of the support for the body fluid assay stripaccording to this invention, the aforesaid carboxymethylcellulose orcarboxyethylcellulose is preferably adjusted to a degree of basesaturation of 20% or more. This is because at less than 20% it isimpossible to obtain paper having such water dispersibility andsolubility as to be flushed down the toilet.

It is noted that the regulation of the degree of base saturation of thefibrous carboxymethylcellulose or carboxylethylcellulose forming a majorfibrous part of the above-mentioned paper, the pH regulation of thesurface of the above-mentioned paper to be provided with a reagent layerand the pH regulation of a solution or dispersion of the above-mentionedpaper are easily achievable in the steps of processing into paper thepaper-making material composed mainly of the fibrouscarboxymethylcellulose or carboxyethylcellulose having a degree ofetherification of 0.1 to 1.0. In other words, these are attainable by afirst paper-making step in which an aqueous solution of an alkali metalcompound such as carbonate of soda or caustic soda is added to wet paperon felt in a slightly excessive amount (more than the neutralizationequivalent of the carboxymethylcellulose or carboxyethylcellulose in thewet paper) to obtain dry paper of about pH 10-11 in which fibrouscellulose glycolate is converted into salts of such metals as Na throughion exchange, and a second step in which the obtained dry paper istreated by a dilute acid.

More specifically, if the aqueous solution of the alkali metal compoundis added to the wet paper on felt during the paper-making course ofprocessing a papermaking feed composed mainly of fibrouscarboxymethylcellulose or carboxyethylcellulose, then theabove-mentioned dry paper can be obtained by continuous operationwithout inflicting on the wet paper such damages as incidental cutting,since the above-mentioned felt serves as a reinforcing belt for the wetpaper.

It is noted that if an aqueous solution containing an organic solventsuch as methanol or acetone is used as the above-mentioned aqueoussolution of the alkali metal compound, it is then possible to moreeffectively prevent the wet paper from suffering damage in the course ofthe above-mentioned alkali treatment.

In the second or acid treatment step wherein the paper material of aboutpH 10-11, in which the major fibrous component is formed of the metal,e.g. Na, salt of fibrous cellulose glycolate, is impregnated with adilute acid to effect local formation of fibrous cellulose glycolate, adilute acid solution, e.g. a dilute hydrochloric acid solution may beapplied uniformly to the paper, while regulating its pH. However, thisoften causes the reverse reaction of --COOH --COONa to take placelocally and noticeably, in which case difficulty will be encountered informing uniform fibrous cellulose glycolate having a degree of basesaturation of 20% or more.

For that reason, the above-mentioned acid treatment is preferablycarried out with a solution obtained by dissolving an organic acid in amixed solvent of water with an organic solvent, said organic acid havingan acid-in-water index or pKa--the cologarithm of its dissociation inwater--increased to 3 or more.

More specifically, when the acid treatment is carried out with thesolution in which an organic acid having an acid-in-water indexincreased to 3 or more is dissolved in a mixed solvent of water with anorganic solvent, it is possible to effectively limit the extent of alowering of the degree of base saturation of the metal, e.g. Na, salt offibrous cellulose glycolate. To this end, use is preferably made of anabout 0.3 to 10 wt. % solution of an acid having an acid-in-water indexincreased to 3 or more, such as acetic, succinic, lactic, glycolic,malic or tartaric acid, in the mixed solvent of water with an organicsolvent.

It is noted that the preferred organic solvent in the above-mentionedmixed solvent is an alcohol such as methyl alcohol, ethyl alcohol,propyl alcohol and butyl alcohol; acetone; methyl ethyl ketone; methylpropyl ketone; and so on. For the reason that the presence of theabovementioned organic solvent in the mixed solvent plays a role inlimiting the extent of a decrease in the base saturation of theabove-mentioned fibrous carboxymethylcellulose or carboxyethylcellulose,the mixed solvent preferably contains more than 30 wt. % of the organicsolvent.

It is noted that while the degree of base saturation of the fibrouscarboxymethylcellulose or carboxyethylcellulose obtained at theabove-mentioned acid treatment step is determined by the degree ofetherification of carboxymethylcellulose or carboxyethylcellulose, thetype of the acid available, the acid-in-water index of the acidavailable, the composition of the mixed solvent, the acid concentrationof the processing solution and the coating rate of the processingsolution. However, this is primarily determined by the acidconcentration of the processing solution, if the rest is all identical.By performing the acid treatment under the conditions determined bypreliminary experimentation, it is thus possible and advantageous toobtain paper in which the fibrous carboxymethylcellulose orcarboxyethylcellulose forming its major fibrous part has a degree ofbase saturation maintained at 20% or more and which, upon disintegratedby water, provides a solution or dispersion whose pH lies in the rangeof 5.0 to 8.0.

A water-soluble and -dispersible resin coat or coats formed on either orboth sides of the above-mentioned water-dispersible and -soluble fibroussubstrate is or are provided with an assay reagent layer formed of, e.g.a mixed resin of polyvinyl pyrrolidone with polyvinyl butyral, saidassay reagent layer being firmly and integrally bonded thereto.

In what follows, the water-disintegrable composition will be explained.

According to one aspect of this invention, there is provided acoat-forming composition comprising a mixed resin of at least onewater-insoluble resin capable of forming a film having a saturationhygroscopicity less than 15% at a 90% relative humidity with at leastone water-soluble resin capable of forming a film having a saturationhygroscopicity of 15% or more at a 90 relative humidity, and a solventin which both the resins can dissolve.

According to another aspect of this invention, there is provided a coatforming composition as mentioned above, wherein the mixed resin in asolvent solution comprises polyvinyl pyrrolidone and polyvinyl butyral.

According to a further aspect of this invention, there is provided acoat-forming composition as mentioned above, the mixed resin in asolvent solution comprises 95 to 50 parts by weight of polyvinylpyrrolidone with 5 to 50 parts by weight of polyvinyl butyral

According to a still further aspect of this invention, there is provideda coat-forming composition as mentioned in any one of the 1st to 3rdaspects, wherein the solvent is an alcohol such as amyl alcohol.

In the coat-forming compositions according to this invention, the resincapable of forming a film having a saturation hygroscopicity less than15% at a 90% relative humidity is a hydrophobic resin. For example, useis preferably made of the following resins.

    ______________________________________                                        Type of Film      Saturation Hygroscopicity                                   ______________________________________                                        Polyisobutyl ether                                                                              1.2%                                                        Polymethyl methacrylate                                                                         1.4%                                                        Polyvinyl acetate 3.1%                                                        Polyvinyl butyral 3.5%                                                        Cellulose acetate with a                                                                        10.5%                                                       degree of substitution or DS                                                  of 2.3                                                                        ______________________________________                                    

The resin capable of forming a film having a saturation hygroscopicityof 15% or more at a 90% relative humidity is a hydrophilic resin. Forinstance, use is preferably made of the following resins.

    ______________________________________                                        Type of Film     Saturation Hygroscopicity                                    ______________________________________                                        Sodium polyacrylate                                                                            151.7%                                                       Polyvinyl pyrrolidone                                                                          67.9%                                                        Polyacrylic acid 47.5%                                                        Polyvinylmethoxy acetal with                                                                   42.3%                                                        an acetal content of 48%                                                      Polyvinylamine (75% RH)                                                                        39.5%                                                        Polyvinyl alcohol                                                                              26.4%                                                        Viscose          22.1%                                                        Cellulose acetate with a DS                                                                    22.0%                                                        of 0.8                                                                        Polyethylene oxide                                                                             18.0%                                                        Polyvinylmethoxy acetal with                                                                   16.3%                                                        an acetal content of 86%                                                      ______________________________________                                    

In the present invention, not only such alcohols as mentioned above butalso hydrophilic group-containing organic solvents such as dioxane andanisole may be used as the solvent in which the above-mentioned tworesins can dissolve.

The coat-forming composition--one embodiment of this invention--appliedto the above-mentioned water-dispersible and -soluble fibrous substrateis provided to retain the surface of the support provided with an assayreagent layer in the form of a complete film in water for a certainshort period of time. For instance, when the assay reagent layer isformed of a coat layer, it serves to prevent the coating agent forforming the coat layer from penetrating through the support.

When the coat-forming composition formed of the mixed resin of polyvinylpyrrolidone with polyvinyl butyral--one embodiment of the coat-formingcomposition according to this invention--is used for a body fluid assaystrip, that mixed resin should not contain 95% by weight or less ofpolyvinyl pyrrolidone. This is because at more than 95% the support'ssurface is so poor in toughness that it is drastically broken when abody fluid sample is injected directly onto the body fluid assay strip.

When the resin coat-forming mixed resin of polyvinyl pyrrolidone withpolyvinyl butyral contains less than 50 by weight of polyvinylpyrrolidone, the support cannot be flushed down the toilet due to itsdecreased water-solubility and -dispersibility.

EXAMPLE A

A mixed feed of 80 parts by weight of fibrous carboxymethylcellulosehaving a degree of etherification of 0.54 and 20 parts by weight ofbleached kraft pulp was processed to a degree of beating of 20° SR intoa starting material for paper making. This starting material was formedinto sizeless paper at a rate of 20 m/min by means of a cylinder papermachine, while an 8% by weight aqueous solution of carbonate of soda wascoated on the wet paper being formed, thereby obtaining alkaline paper(a) having a weight of 120 g/m².

Subsequently, a 1.25% by weight dilute acid solution of acetic acid andcitric acid (at a weight ratio of 2:3) dissolved in a mixture of equalamounts of methanol and water was roll-coated on the paper (a) to acoverage of 1.9 g/m², calculated as acid matter, followed by drying. Inthis way, neutral paper (b) was obtained, which formed part of thesupport of a body fluid assay strip according to one embodiment of thisinvention.

The thus obtained paper (b) shows pH 5.8 on its acid treated surface,and provides an aqueous dispersion of pH 7.2. The alkaline paper (a) hasa volume of base substitution of 2.79 meq/g (as calculated), and theneutral paper (b) shows a degree of base saturation of 65.1%.

(a) COMPARATIVE EXAMPLE A

A bleached kraft pulp feed having a degree of beating of 20° SR wasprocessed into comparative paper (c) having a weight of 120 g/m² at arate of 20 m/min by means of a cylinder paper machine.

Experiment 1

About 500 cc of water placed in a beaker were agitated by means of astirrer until stable, 3 to 4-cm high vortices were obtained. Then, astrip of 8 x 80 mm of each of the paper (b) obtained in Example A, thepaper (c) obtained in Comparative Example A and the paper (a) obtainedin the course of Example A was put in the water to determine its waterdispersibility.

The results are given below.

Paper (a) . . . Outstandingly good

Paper (b) . . . Good

Paper (c) . . . Bad

Experiment 2

The paper (a) obtained in Example A, the paper (c) obtained inComparative Example A and the paper (a) obtained in the course ofExample A were each used as the support of a pH indicator. To this end,the following ink composition was screen-printed on the support in theform of a reagent layer.

It is noted that for printing the aforesaid reagent layer, an 80-meshscreen printing plate was used, with the total thickness of the resistand screen gauze being 190 μm. Ink Composition for pH Detection (inparts by weight p.b.w. for short)

    ______________________________________                                        Methyl Red              0.070  p.b.w.                                         Bromothymol Blue        1.0    p.b.w.                                         Dodecyltrimethylammonium chloride                                                                     1.0    p.b.w.                                         Polyvinyl pyrrolidone   8.3    p.b.w.                                         Polyvinyl butyral       4.1    p.b.w.                                         Fine cellulose powders  174.0  p.b.w.                                         Butyl Cellosolve        226.9  p.b.w.                                         Butyl Cellosolve acetate                                                                              22.0   p.b.w.                                         Sodium hydroxide        0.098  p.b.w                                          Water                   2.0    p.b.w.                                         ______________________________________                                    

Furthermore, dilute hydrochloric acid and caustic soda solutions wereadded to normal urine to prepare urine samples regulated to pH 5, 6, 7,8 and 9. The aforesaid three pH indicator papers were immersed in thesesamples. The indicator paper using the paper (b) as the support wascolored in the same pH color as that on a separately provided controltable, but the indicators using the papers (a) and (c) as the supportswere in no agreement with the corresponding colors on the control table.

The present supports for body fluid assay strips each contain as themain fibrous component fibrous carboxymethylcellulose orcarboxyethylcellulose having a degree of etherification of 0.1 to 1.0,with the degree of base saturation being adjusted to 20% or more. Thus,they are well dissolved or dispersed in water and have some thicknessenough to meet the suitable rigidity required for supports forming partof body fluid assay strips to have, yet they can be disposed of intoilet facilities after use.

Accordingly, the body fluid assay strips comprising the present supportshave some advantages of being easy for the users to dispose of, beingsanitary, and so on.

As mentioned above, the paper forming part of the support according tothis invention provides a solution or dispersion with its pH rangingfrom 5.0 to 8.0. Thus, when measuring the pH of the body fluids to beexamined or assaying body fluids with the use of reagent layerspreregulated to acidity, like those for detecting glucose, protein,urobilinogen, etc., the pH of the region to be examined is unlikely tobe affected by the support itself.

With the body fluid assay strip comprising the present support,therefore, it is possible to obtain precise results of examinationwithout causing pH changes, which may otherwise take place due to bodyfluid assay strips, to be reflected in the reaction of the reagentlayer.

EXAMPLE B

In the description that follows, the illustrative construction of thecomposition for forming a coat according to this invention and how touse it will be explained with reference to an embodiment in which saidcomposition is applied to the support of a body fluid assay strip.

Water-Dispersible and -Soluble, Fibrous Material

A mixed feed of 80 parts by weight of fibrous carboxymethylcellulosehaving a degree of etherification of 0.54 and 20 parts by weight ofbleached kraft pulp was processed to a degree of beating of 20° SR intoa starting material for paper making. This starting material was formedinto sizeless paper at a rate of 20 m/min by means of a cylinder papermachine, while an 8% by weight aqueous solution of carbonate of soda wascoated on the wet paper being formed, thereby obtaining alkaline paper(A) having a weight of 120 g/m².

Subsequently, a 1.25% by weight dilute acid solution of acetic acid andcitric acid (at a weight ratio of 2:3) dissolved in a mixture of equalamounts of methanol and water was roll-coated on the paper (A) to acoverage of 1.9 g/m², calculated as acid matter, followed by drying. Inthis way, neutral paper (B) was obtained.

The thus obtained paper (B) shows pH 5.8 on its acid treated surface,and provides an aqueous dispersion of pH 7.2. The alkaline paper (A) hasa volume of base substitution calculated to be 2.79 meq/g, and theneutral paper (B) shows a degree of base saturation of 65.1 %.

Formation of Resin Coat on the Surface of Fibrous Material

Using a mixed resin of 90 parts by weight of polyvinyl pyrrolidone--alinear chain polymer of 1-vinyl-2-pyrrolidone having a meanpolymerization degree of about 11,000; Colidone 90 made by BASF AG. and10 parts by weight of polyvinyl butyral--having a polymerization degreeof about 1,700 and a butylation degree of about 65 mol %; Eslec B madeby Sekisui Chemical Co., Ltd.), the aforesaid neutral paper (B) wasprovided on both its sides with resin coats to a coverage of 5.0 g/m² ondry matter basis.

Reference will now be made to the coating agent and manner used forforming the aforesaid coats.

Coating Agent

To obtain this, a given amount of a well-stirred mixture of 15% byweight polyvinyl pyrrolidone with amyl alcohol and a given amount of awell-stirred mixture of 15% by weight of polyvinyl butyral with amylalcohol, both mixtures obtained with the use of a homomixer, were fullymixed together by means of a spatula.

Coating Manner

Coating was carried out with the use of a Miya bar No. 6.

The obtained support for a body fluid assay strip has a waterdispersibility enough to be flushed down the toilet, and possesses sucha surface toughness so as to enable a body fluid sample to be injectedfrom a syringe onto the reagent layer formed thereon, i.e. such asurface toughness as to enable a sample, e.g. a urine sample to beinjected directly onto the reagent layer formed thereon, not via such avessel as a cup. The resin coat provided on the back surface of thesupport is designed to reduce the degree of sagging or warping bywetting of the body fluid assay strip, while the assay result isdetermined.

The coat-forming composition according to this invention comprises analcoholic solvent solution of a mixed resin of a water-insoluble butalcohol-soluble resin capable of forming a film showing a saturationhygroscopicity less than 15% at a 90% relative humidity with awater-soluble and alcohol-soluble resin capable of forming a filmshowing a saturation hygroscopicity of 15% or more at a 90% relativehumidity. By processing that composition by coating or casting, it isthus possible to easily obtain a coat which can retain its film formstably in water for a certain short period of time without being swollenon its surface. It is also possible to obtain a resin coat having awater solubility or water swelling properties enough to be allowed toflow in water, e.g. a coat film which can be used with body fluid assaystrips, curl fit films for hydraulic transfer, etc. so as to afford thedesired water solubility or water swelling properties to them, butenables their form to be stably retained in water for a sufficient, ifnot long, period of time.

EXAMPLE C

In what follows, the illustrative construction of the resin-coatedmaterial according to this invention and how to use it will be explainedwith reference to an embodiment in which said material is used as thesupport for a body fluid assay strip.

Preparation of Water-Soluble or -Dispersible Fibrous Material

A mixed feed of 80 parts by weight of fibrous carboxymethylcellulosehaving a degree of etherification of 0.54 and 20 parts by weight ofbleached kraft pulp was processed to a degree of beating of 20° SR intoa starting material for paper making. This starting material was formedinto sizeless paper at a rate of 20 m/min by means of a cylinder papermachine, while an 8% by weight aqueous solution of soda carbonate wascoated on the wet paper being formed, thereby obtaining alkaline paper(A) having a weight of 120 g/m².

Subsequently, a 1.25% by weight dilute acid solution of acetic acid andcitric acid (at a weight ratio of 2:3) dissolved in a mixture of equalamounts of methanol and water was roll-coated on the paper (A) to acoverage of 1.9 g/m², calculated as acid matter, followed by drying. Inthis way, neutral paper (B) was obtained.

The thus obtained paper (B) shows pH 5.8 on its acid treated surface,and provides an aqueous dispersion of pH 7.2. The alkaline paper (A) hasa volume of base substitution of 2.79 meq/g (as calculated), and theneutral paper (B) shows a degree of base saturation of 65.1%.

Formation of Resin Coat on the Surface of Fibrous Material

Using a mixed resin of 90 parts by weight of polyvinyl pyrrolidone(PVP)--having a mean polymerization degree of about 11,000; Colidone 90made by BASF AG. and 10 parts by weight of polyvinyl butyral--having apolymerization degree of about 1,700 and a butylation degree of about 65mol %; Eslec B made by Sekisui Chemical Co., Ltd.), the aforesaidneutral paper (B) was provided on both its sides with resin coats to acoverage of 5.0 g/m² on dry matter basis, thereby obtaining aresin-coated material embodying this invention.

Reference will now be made to the coating agent and manner used forforming the aforesaid coats.

Coating Agent

To obtain this, a given amount of a well-stirred mixture of 15% byweight polyvinyl pyrrolidone with amyl alcohol and a given amount of awell-stirred mixture of 15% by weight of polyvinyl butyral with amylalcohol, both mixtures obtained with the use of a homomixer, were fullymixed together by means of a spatula.

Coating Manner

Coating was carried out with the use of a Miya bar No. 6.

The obtained resin-coated material embodying this invention has a waterdispersibility enough to be flushed down the toilet, and the resin coatformed on its surface possesses such a surface toughness so as to enablea fluid body sample to be injected from a syringe onto the reagent layerformed thereon, i.e. such a surface toughness as to enable a sample,e.g. a urine sample to be injected directly onto the reagent layerformed thereon, not via such a vessel as a cup. The resin coat providedon the back surface of this material is designed to reduce the degree ofsagging or warping by wetting of the body fluid assay strip, while theassay result is determined.

The aforesaid resin-coated material according to this inventioncomprises a water-soluble and -dispersible fibrous material and awater-soluble and -dispersible resin coat formed on at least one surfacethereof, said resin coat comprising an alcoholic solvent solution of amixed resin of at least one water-insoluble but alcohol-soluble resincapable of forming a film showing a saturation hygroscopicity of 15% orless at a 90% relative humidity with at least one water-soluble andalcohol-soluble resin capable of forming a film showing a saturationhygroscopicity of 15% or more at a 90% relative humidity.

That is, a resin coat, which can retain its film form stably in waterfor a certain short period of time without being swollen on its surfaceand has water-solubility and water-swelling properties enough to beallowed to flow in water, is formed by a coating agent comprising analcoholic solvent solution. In other words, a resin coat, which has thedesired water-swelling properties and water-solubility and can retainits film form stably in water for a sufficient, if not long, length oftime, can be easily obtained by coating.

EXAMPLE D

The illustrative construction of the fluid body assay strip according tothis invention will now be explained with reference to how to prepareit.

Water-Dispersible or -Soluble Fibrous Material

A mixed feed of 80 parts by weight of fibrous carboxymethylcellulosehaving a degree of etherification of 0.54 and 20 parts by weight ofbleached kraft pulp was processed to a degree of beating of 20° SR intoa starting material for paper making. This starting material was formedinto sizeless paper at a rate of 20 m/min by means of a cylinder papermachine, while an 8% by weight aqueous solution of carbonate of soda wascoated on the wet paper being formed, thereby obtaining alkaline paper(A) having a weight of 120 g/m².

Subsequently, a 1.25% by weight dilute acid solution of acetic acid andcitric acid (at a weight ratio of 2:3) dissolved in a mixture of equalamounts of methanol and water was roll-coated on the paper (A) to acoverage of 1.9 g/m², calculated as acid matter, followed by drying. Inthis way, neutral paper (B) was obtained.

The thus obtained paper (B) shows pH 5.8 on its acid treated surface,and provides an aqueous dispersion of pH 7.2. The alkaline paper (A) hasa volume of base substitution of 2.79 meq/g (as calculated), and theneutral paper (B) shows a degree of base saturation of 65.1%.

Formation of Resin Coat on the Surface of Fibrous Material

Using a mixed resin of 90 parts by weight of polyvinyl pyrrolidone(PVP)--having a mean polymerization degree of about 11,000; Colidone 90made by BASF AG. and 10 parts by weight of polyvinyl butyral (Bx-1)having a polymerization degree of about 1,700 and a butylation degree ofabout 65 mol %; Eslec B made by Sekisui Chemical Co., Ltd.) in theamounts indicated in Table 1, the aforesaid neutral paper (B) wasprovided on one surface with a resin coat to a coverage of 5.0 g/m² ondry matter basis, thereby obtaining supports for body fluid assaystrips.

Reference will now be made to the coating agent and manner used forforming the aforesaid coats.

Coating Agent

To obtain this, a given amount of a well-stirred mixture of 15% byweight polyvinyl pyrrolidone with amyl alcohol and a given amount of awell-stirred mixture of 15% by weight of polyvinyl butyral with amylalcohol, both mixtures obtained with the use of a homomixer, were fullymixed together by means of a spatula.

Coating Manner

Coating was carried out with the use of a Miya bar No. 1.

                  TABLE 1                                                         ______________________________________                                                    Composition of Surface Resin Coats                                Type of Supports                                                                            (PVP)       (Bx-1)                                              ______________________________________                                        (a-1)         100          0                                                  (a-2)         95           5                                                  (a-3)         90          10                                                  (a-4)         80          20                                                  (a-5)         70          30                                                  (a-6)         60          40                                                  (a-7)         50          50                                                  (a-8)         30          70                                                  ______________________________________                                    

In the instant example, the aforesaid supports (a-1) to (a-8) for bodyfluid assay strips were used along with a control support formed of theaforesaid paper (B). Each of the resin-coated supports was designed suchthat when it was cut into a rectangular flat strip of 8 mm ×80 mm, asquare flat region of 5 mm ×5 mm to receive a reagent layer was left inthe vicinity of the strip's end. A glucose assay reagent layer composedof the following components was printed on that region by means of an8-mesh screen printing plate.

    ______________________________________                                        Composition for Glucose Assay Reagent                                         ______________________________________                                        Glucose oxidase         3.6    p.b.w.                                         Peroxidase              2.4    p.b.w.                                         Guaiac fat              4.8    p.b.w.                                         Sorbitan monolaurate    7.2    p.b.w.                                         L-ascorbyl stearate     0.24   p.b.w.                                         Citric acid             2.8    p.b.w.                                         Soda citrate            11.0   p.b.w.                                         Polyvinyl pyrrolidone (Colidone 90                                                                    12.6   p.b.w.                                         made by BASF AG)                                                              Polyvinyl butyral (Eslec BX-1 made                                                                    2.25   p.b.w.                                         by Sekisui Chemical Co., Ltd.)                                                Fine cellulose powders (Abycell TG-D                                                                  171    p.b.w.                                         made by Asahi Chemical Industry,                                              Co., Ltd.)                                                                    n-Amyl alcohol          171    p.b.w.                                         Butyl Cellosolve acetate                                                                              67     p.b.w.                                         ______________________________________                                    

Each of the aforesaid supports provided with the reagent layers was cutinto rectangular flat strips of 8 mm ×80 mm, having square flat reagentlayers of 5 mm ×5 mm near their ends, thereby obtaining body fluid assaystrips embodying this invention. In similar manners, a control strip wasobtained.

Experiment 3

About 500 cc of water placed in a beaker were agitated by means of astirrer until 3 to 4-cm high, stable vortices were obtained. Then, eachof the body fluid assay strips of (8 mm ×80 mm) was put in water tomeasure the length of time (seconds) required for it to disperse indiscrete lumps.

The obtained results of the water-solubility and dispersibility tests ofthe strips are reported in Table 2.

It is understood that an index to whether or not the strips can beflushed down the toilet is at most 700 seconds in terms of the length oftime required for them to disperse in discrete lumps.

                  TABLE 2                                                         ______________________________________                                        Type of Supports for Assay Strips                                                                Dispersing time (sec.)                                     ______________________________________                                        (a-1)              13                                                         (a-2)              16                                                         (a-3)              20                                                         (a-4)              33                                                         (a-5)              55                                                         (a-6)              100                                                        (a-7)              300                                                        (a-8)              undispersed                                                (B)                13                                                         ______________________________________                                    

Experiment 4

Each of the body fluid assay strips obtained in the above-mentionedexamples and comparative example was fixed at the end opposite to thereagent layer carrying end, and tilted and held at an angle of 45° withrespect to horizontal. With a syringe spaced 10 mm away from the strip,3 ml of water was sprayed onto the central region--located about 40 mmaway from the reagent layer carrying end--of the reagent layer carryingside of the strip for 2 seconds, followed by two water injections. Then,the strip was held horizontally for 60 seconds. After that, how much thestrip was marred on the surface was observed. It was found that thecontrol support (B) and the support (a-1) treated on the surface with100% polyvinyl pyrrolidone resin were both marred on the reagent layercarrying surfaces However, the surface coats of other supports werefound to have a water resistance sufficient to stand up to the syringetests.

Experiment 5

Two supports (a-1) and (a-1), . . . , or two supports (B) and (B) wereput on each other while their reagent layers were brought in contactwith each other. While a load of 20 g/cm² was applied over the striplaminate from above, it was allowed to stand in an atmosphere of 40° C.and 50% RH for 12 hours. After that, one strip was released from theother by a finger tip to observe whether or not blocking took place. Theresults are reported in Table 3.

                  TABLE 3                                                         ______________________________________                                        Type of Supports for Assay Strips                                                                  Blocking                                                 ______________________________________                                        (a-1)                Blocking occurred                                        (a-2)                No blocking                                              (a-3)                No blocking                                              (a-4)                No blocking                                              (a-5)                No blocking                                              (a-6)                No blocking                                              (a-7)                No blocking                                              (a-8)                No blocking                                              (B)                  No blocking                                              ______________________________________                                    

Likewise, two supports (a-1) and (a-1), . . . , or two supports (B) and(B) were put on each other while the reagent layer side of one strip wasbrought in contact with the reagent layer-free side of the other. Insimilar manners as mentioned above, whether or not blocking took placewas observed. It was found that all the strips showed no sign ofblocking whatsoever.

EXAMPLE E Water-Dispersible or -Soluble Fibrous Material

A mixed feed of 80 parts by weight of fibrous carboxymethylcellulosehaving a degree of etherification of 0.54 and 20 parts by weight ofbleached kraft pulp was processed to a degree of beating of 20° SR intoa starting material for paper making. This starting material was formedinto sizeless paper at a rate of 20 m/min by means of a cylinder papermachine, while an 8% by weight aqueous solution of soda carbonate wascoated on the wet paper being formed, thereby obtaining alkaline paper(A) having a weight of 120 g/m².

Subsequently, a 1.25% by weight dilute acid solution of acetic acid andcitric acid (at a weight ratio of 2:3) dissolved in a mixture of equalamounts of methanol and water was roll-coated on the paper (A) to acoverage of 1.9 g/m², calculated as acid matter, followed by drying. Inthis way, neutral paper (B) was obtained.

The thus obtained paper (B) shows pH 5.8 on its acid treated surface,and provides an aqueous dispersion of pH 7.2. The alkaline paper (A) hasa volume of base substitution of 2.79 meq/g (as calculated), and theneutral paper (B) shows a degree of base saturation of 65.1%.

Formation of Resin Coat on the Surface of Fibrous Material

Using a mixed resin of 90 parts by weight of polyvinyl pyrrolidone(PVP)--having a mean polymerization degree of about 11,000; Colidone 90made by BASF AG. and 10 parts by weight of polyvinyl butyral(Bx-1)having a polymerization degree of about 1,700 and a butylation degree ofabout 65mol %; Eslec B made by Sekisui Chemical Co., Ltd.) in theamounts indicated in Table 1, the aforesaid neutral paper (B) wasprovided on one surface with a resin coat to a coverage of 5.0 g/m² ondry matter basis. After that, that paper was provided on the other sidewith a coat 5.0 g/m² on dry basis--formed of resins indicated in Table4, thereby obtaining supports for body fluid assay strips.

Reference will now be made to the coating agent and manner used forforming the aforesaid coats.

Coating Agent

To obtain this, a given amount of a well-stirred mixture of 15% byweight of polyvinyl pyrrolidone with amyl alcohol and a given amount ofa well-stirred mixture of 15% by weight of polyvinyl butyral with amylalcohol, both mixtures obtained with the use of a homomixer, were fullymixed together by means of a spatula.

Coating Manner

Coating was carried out with the use of a Miya bar No. 6.

                  TABLE 4-1                                                       ______________________________________                                        Back-Surface Resin Coat                                                       100% Polyvinyl Pyrrolidone                                                                Composition of Surface Resin Coats                                Type of Supports                                                                            (PVP)       (Bx-1)                                              ______________________________________                                        (b-1)         100          0                                                  (b-2)         95           5                                                  (b-3)         90          10                                                  (b-4)         80          20                                                  (b-5)         70          30                                                  (b-6)         60          40                                                  (b-7)         50          50                                                  (b-8)         30          70                                                  ______________________________________                                    

                  TABLE 4-2                                                       ______________________________________                                        Back-Surface Resin Coat                                                       95% Polyvinyl Pyrrolidone                                                     5% Polyvinyl Butyral                                                                      Composition of Surface Resin Coats                                Type of Supports                                                                            (PVP)       (Bx-1)                                              ______________________________________                                        (c-1)         100         0                                                   (c-2)         95          5                                                   (c-3)         90          10                                                  (c-4)         80          20                                                  (c-5)         70          30                                                  (c-6)         60          40                                                  (c-7)         50          50                                                  (c-8)         30          70                                                  ______________________________________                                    

                  TABLE 4-3                                                       ______________________________________                                        Back-Surface Resin Coat                                                       95% Polyvinyl Pyrrolidone                                                     10% Polyvinyl Butyral                                                                     Composition of Surface Resin Coats                                Type of Supports                                                                            (PVP)       (Bx-1)                                              ______________________________________                                        (d-1)         100         0                                                   (d-2)         95          5                                                   (d-3)         90          10                                                  (d-4)         80          20                                                  (d-5)         70          30                                                  (d-6)         60          40                                                  (d-7)         50          50                                                  (d-8)         30          70                                                  ______________________________________                                    

                  TABLE 4-4                                                       ______________________________________                                        Back-Surface Resin Coat                                                       80% Polyvinyl Pyrrolidone                                                     20% Polyvinyl Butyral                                                                     Composition of Surface Resin Coats                                Type of Supports                                                                            (PVP)       (Bx-1)                                              ______________________________________                                        (e-1)         100         0                                                   (e-2)         95          5                                                   (e-3)         90          10                                                  (e-4)         80          20                                                  (e-5)         70          30                                                  (e-6)         60          40                                                  (e-7)         50          50                                                  (e-8)         30          70                                                  ______________________________________                                    

                  TABLE 4-5                                                       ______________________________________                                        Back-Surface Resin Coat                                                       70% Polyvinyl Pyrrolidone                                                     30% Polyvinyl Butyral                                                                     Composition of Surface Resin Coats                                Type of Supports                                                                            (PVP)       (Bx-1)                                              ______________________________________                                        (f-1)         100         0                                                   (f-2)         95          5                                                   (f-3)         90          10                                                  (f-4)         80          20                                                  (f-5)         70          30                                                  (f-6)         60          40                                                  (f-7)         50          50                                                  (f-8)         30          70                                                  ______________________________________                                    

                  TABLE 4-6                                                       ______________________________________                                        Back-Surface Resin Coat                                                       60% Polyvinyl Pyrrolidone                                                     40% Polyvinyl Butyral                                                                     Composition of Surface Resin Coats                                Type of Supports                                                                            (PVP)       (Bx-1)                                              ______________________________________                                        (g-1)         100         0                                                   (g-2)         95          5                                                   (g-3)         90          10                                                  (g-4)         80          20                                                  (g-5)         70          30                                                  (g-6)         60          40                                                  (g-7)         50          50                                                  (g-8)         30          70                                                  ______________________________________                                    

                  TABLE 4-7                                                       ______________________________________                                        Back-Surface Resin Coat                                                       50% Polyvinyl Pyrrolidone                                                     50% Polyvinyl Butyral                                                                     Composition of Surface Resin Coats                                Type of Supports                                                                            (PVP)       (Bx-1)                                              ______________________________________                                        (h-1)         100         0                                                   (h-2)         95          5                                                   (h-3)         90          10                                                  (h-4)         80          20                                                  (h-5)         70          30                                                  (h-6)         60          40                                                  (h-7)         50          50                                                  (h-8)         30          70                                                  ______________________________________                                    

                  TABLE 4-8                                                       ______________________________________                                        No Back-Surface Resin Coat                                                                Composition of Surface Resin Coats                                Type of Supports                                                                            (PVP)       (Bx-1)                                              ______________________________________                                        (i-1)         100         0                                                   (i-2)         95          5                                                   (i-3)         90          10                                                  (i-4)         80          20                                                  (i-5)         70          30                                                  (i-6)         60          40                                                  (i-7)         50          50                                                  (i-8)         30          70                                                  ______________________________________                                    

In the instant example, the aforesaid supports (a-1) to (i-8) for bodyfluid assay strips were used along with a control support formed of theaforesaid paper (B) provided on both its sides with no coating agent.Each of the resin-coated supports was designed such that when it was cutinto a rectangular flat strip of 8 mm ×80 mm, a square flat region of 5mm ×5 mm to receive a reagent layer was left on the surface coat in thevicinity of the strip's end. A glucose assay reagent layer composed ofthe following components was printed on that region by means of an8-mesh screen printing plate.

    ______________________________________                                        Composition for Glucose Assay Reagent                                         ______________________________________                                        Glucose oxidase          3.6    p.b.w.                                        Peroxidase               2.4    p.b.w.                                        Guaiac fat               4.8    p.b.w.                                        Sorbitan monolaurate     7.2    p.b.w.                                        L-ascorbyl stearate      0.24   p.b.w.                                        Citric acid              2.8    p.b.w.                                        Soda citrate             11.0   p.b.w.                                        Polyvinyl pyrrolidone (Colidone 90                                                                     12.6   p.b.w.                                        made by BASF AG)                                                              Polyvinyl butyral (Eslec BX-1 made                                                                     2.25   p.b.w.                                        by Sekisui Chemical Co., Ltd.)                                                Fine cellulose powders (Abycell TG-D                                                                   171    p.b.w.                                        made by Asahi Chemical Industry,                                              Co., Ltd.)                                                                    n-Amyl alcohol           171    p.b.w.                                        Butyl Cellosolve acetate 67     p.b.w.                                        ______________________________________                                    

Each of the aforesaid supports provided with the reagent layers was cutinto rectangular flat strips of 8 mm ×80 mm, having square flat reagentlayers of 5 mm ×5 mm near their ends, thereby obtaining body fluid assaystrips embodyinq this invention. In similar manners, a control strip wasobtained

Experiment 6

About 500 cc of water placed in a beaker were agitated by means of astirrer until 3 to 4-cm high, stable vortices were obtained. Then, eachof the body fluid assay strips of (8 mm ×80 mm) was put in water tomeasure the length of time (seconds) required for it to disperse indiscrete lumps.

The obtained results of the water-solubility and dispersibility tests ofthe strips are reported in Table 5.

It is understood that an index to whether or not the strips can beflushed down the toilet is not greater than 700 seconds in terms of thelength of time required for them to disperse in discrete lumps.

                  TABLE 5-1                                                       ______________________________________                                        Type of Supports for Assay Strips                                                                 Dispersing time (sec.)                                    ______________________________________                                        (b-1)               16                                                        (b-2)               21                                                        (b-3)               28                                                        (b-4)               42                                                        (b-5)               61                                                        (b-6)               110                                                       (b-7)               300                                                       (b-8)               undispersed                                               (B)                 13                                                        ______________________________________                                    

                  TABLE 5-2                                                       ______________________________________                                        Type of Supports for Assay Strips                                                                 Dispersing time (sec.)                                    ______________________________________                                        (c-1)               21                                                        (c-2)               25                                                        (c-3)               32                                                        (c-4)               45                                                        (c-5)               62                                                        (c-6)               119                                                       (c-7)               312                                                       (c-8)               undispersed                                               ______________________________________                                    

                  TABLE 5-3                                                       ______________________________________                                        Type of Supports for Assay Strips                                                                 Dispersing time (sec.)                                    ______________________________________                                        (d-1)               28                                                        (d-2)               32                                                        (d-3)               37                                                        (d-4)               49                                                        (d-5)               67                                                        (d-6)               130                                                       (d-7)               320                                                       (d-8)               undispersed                                               ______________________________________                                    

                  TABLE 5-4                                                       ______________________________________                                        Type of Supports for Assay Strips                                                                 Dispersing time (sec.)                                    ______________________________________                                        (e-1)               43                                                        (e-2)               46                                                        (e-3)               49                                                        (e-4)               57                                                        (e-5)               70                                                        (e-6)               150                                                       (e-7)               345                                                       (e-8)               undispersed                                               ______________________________________                                    

                  TABLE 5-5                                                       ______________________________________                                        Type of Supports for Assay Strips                                                                 Dispersing time (sec.)                                    ______________________________________                                        (f-1)               59                                                        (f-2)               62                                                        (f-3)               65                                                        (f-4)               69                                                        (f-5)               79                                                        (f-6)               190                                                       (f-7)               360                                                       (f-8)               undispersed                                               ______________________________________                                    

                  TABLE 5-6                                                       ______________________________________                                        Type of Supports for Assay Strips                                                                 Dispersing time (sec.)                                    ______________________________________                                        (g-1)               110                                                       (g-2)               120                                                       (g-3)               130                                                       (g-4)               150                                                       (g-5)               195                                                       (g-6)               265                                                       (g-7)               430                                                       (g-8)               undispersed                                               ______________________________________                                    

                  TABLE 5-7                                                       ______________________________________                                        Type of Supports for Assay Strips                                                                 Dispersing time (sec.)                                    ______________________________________                                        (h-1)               300                                                       (h-2)               310                                                       (h-3)               320                                                       (h-4)               340                                                       (h-5)               370                                                       (h-6)               440                                                       (h-7)               600                                                       (h-8)               undispersed                                               ______________________________________                                    

                  TABLE 5-8                                                       ______________________________________                                        Type of Supports for Assay Strips                                                                 Dispersing time (sec.)                                    ______________________________________                                        (i-1)               13                                                        (i-2)               16                                                        (i-3)               20                                                        (i-4)               33                                                        (i-5)               55                                                        (i-6)               100                                                       (i-7)               300                                                       (i-8)               undispersed                                               ______________________________________                                    

Experiment 7

Each of the body fluid assay strips obtained in the above-mentionedexamples and comparative example was fixed at the end opposite to thereagent layer carrying end, and tilted and held at an angle of 45° withrespect to horizontal. With a syringe spaced 10 mm away from the strip,3 ml of water was sprayed onto the central region--located about 40 mmaway from the reagent layer carrying end--of the reagent layer carryingside of the strip for 2 seconds, followed by two water injections. Then,the strip was held horizontally for 60 seconds. After that, how much thestrip was marred on the surface was observed. It was found that thecontrol support untreated on both its sides and the support treated onthe surface with 100% polyvinyl pyrrolidone resin were both marred onthe reagent layer carrying surfaces. However, the surface coats of othersupports were found to have a water resistance sufficient to stand up tothe syringe tests.

Experiment 8

In similar manners as explained in Experiment 7, each of the body fluidassay strips obtained in the above-mentioned examples and comparativeexample was fixed at the end opposite to the reagent layer carrying end,and tilted and held at an angle of 45° with respect to horizontal. Witha syringe spaced 10 mm away from the strip, 3 ml of water was sprayedonto the central region--located about 40 mm away from the reagent layercarrying end--of the reagent layer carrying side of the strip for 2seconds, followed by two water injections. Then, the strip was holdhorizontally for 60 seconds, after which the angle -θ- of sagging of thestrip was measured.

The results are reported in Table 6, in which the angle θ of sagging ofthe strip refers to the angle of bending of the reagent layer-free sideof the strip.

At an angle θ smaller than 110 or at a larger angle of sagging, theassay strip offers a handling problem when a body fluid sample isinjected directly onto the strip, because considerable difficulty isinvolved in confirming its color changes.

                  TABLE 6-1                                                       ______________________________________                                        Type of Supports Angle θ                                                ______________________________________                                        (b-1)            102                                                          (b-2)            110                                                          (b-3)            118                                                          (b-4)            124                                                          (b-5)            130                                                          (b-6)            132                                                          (b-7)            138                                                          ______________________________________                                    

                  TABLE 6-2                                                       ______________________________________                                        Type of Supports Angle θ                                                ______________________________________                                        (c-1)            111                                                          (c-2)            116                                                          (c-3)            118                                                          (c-4)            125                                                          (c-5)            130                                                          (c-6)            132                                                          (c-7)            137                                                          ______________________________________                                    

                  TABLE 6-3                                                       ______________________________________                                        Type of Supports Angle θ                                                ______________________________________                                        (d-1)            118                                                          (d-2)            119                                                          (d-3)            120                                                          (d-4)            129                                                          (d-5)            134                                                          (d-6)            134                                                          (d-7)            137                                                          ______________________________________                                    

                  TABLE 6-4                                                       ______________________________________                                        Type of Supports Angle θ                                                ______________________________________                                        (e-1)            124                                                          (e-2)            126                                                          (e-3)            132                                                          (e-4)            142                                                          (e-5)            145                                                          (e-6)            146                                                          (e-7)            146                                                          ______________________________________                                    

                  TABLE 6-5                                                       ______________________________________                                        Type of Supports Angle θ                                                ______________________________________                                        (f-1)            130                                                          (f-2)            133                                                          (f-3)            140                                                          (f-4)            149                                                          (f-5)            155                                                          (f-6)            155                                                          (f-7)            156                                                          ______________________________________                                    

                  TABLE 6-6                                                       ______________________________________                                        Type of Supports Angle θ                                                ______________________________________                                        (g-1)            134                                                          (g-2)            138                                                          (g-3)            142                                                          (g-4)            150                                                          (g-5)            153                                                          (g-6)            159                                                          (g-7)            159                                                          ______________________________________                                    

                  TABLE 6-7                                                       ______________________________________                                        Type of Supports Angle θ                                                ______________________________________                                        (h-1)            140                                                          (h-2)            144                                                          (h-3)            149                                                          (h-4)            150                                                          (h-5)            155                                                          (h-6)            158                                                          (h-7)            160                                                          ______________________________________                                    

                  TABLE 6-8                                                       ______________________________________                                        Type of Supports Angle θ                                                ______________________________________                                        (i-1)            90                                                           (i-2)            90                                                           (i-3)            90                                                           (i-4)            90                                                           (i-5)            90                                                           (i-6)            90                                                           (i-7)            90                                                           ______________________________________                                    

EXAMPLE F Coating Agent

To obtain this, a given amount of a well-stirred mixture of 15% byweight of polyvinyl pyrrolidone with 1,4-dioxane and a given amount of awell-stirred mixture of 15% by weight of polyvinyl butyral with1,4-dioxane, both mixtures obtained with the use of a homomixer, werefully mixed together by means of a spatula.

Coating Manner

Coating was carried out with the use of a Miya bar No. 6.

In the instant example, the aforesaid supports (j-1) to (j-8) for bodyfluid assay strips, set out in Table 7, were used along with a controlsupport formed of the aforesaid paper (B). Each of the resin-coatedsupports was designed such that when it was cut into a rectangular flatstrip of 8 mm ×80 mm, a square flat region of 5 mm ×5 mm to receive areagent layer was left in the vicinity of the strip's end. A glucoseassay reagent layer composed of the following components was printed onthat region by means of an 8-mesh screen printing plate.

    ______________________________________                                        Composition for Glucose Assay Reagent                                         ______________________________________                                        Glucose oxidase          3.6    p.b.w.                                        Peroxidase               2.4    p.b.w.                                        Guaiac fat               4.8    p.b.w.                                        Sorbitan monolaurate     7.2    p.b.w.                                        L-ascorbyl stearate      0.24   p.b.w.                                        Citric acid              2.8    p.b.w.                                        Soda citrate             11.0   p.b.w.                                        Polyvinyl pyrrolidone (Colidone 90                                                                     12.6   p.b.w.                                        made by BASF AG)                                                              Polyvinyl butyral (Eslec BX-1 made                                                                     2.25   p.b.w.                                        by Sekisui Chemical Co., Ltd.)                                                Fine cellulose powders (Abycell TG-D                                                                   171    p.b.w.                                        made by Asahi Chemical Industry,                                              Co., Ltd.)                                                                    n-Amyl alcohol           171    p.b.w.                                        Butyl Cellosolve acetate 67     p.b.w.                                        ______________________________________                                    

Each of the aforesaid supports provided with the reagent layers was cutinto rectangular flat strips of 8 mm ×80 mm, having square flat reagentlayers of 5 mm ×5 mm near their ends, thereby obtaining body fluid assaystrips embodying this invention. In similar manners, a control strip wasobtained.

Experiment 9

About 500 cc of water placed in a beaker were agitated by means of astirrer until 3 to 4-cm high, stable vortices were obtained. Then, eachof the body fluid assay strips of (8 mm ×80 mm) was put in water tomeasure the length of time (seconds) required for it to disperse indiscrete lumps.

The obtained results of the strips' water-solubility and -dispersibilitytests are reported in Table 8.

It is understood that an index to whether or not the strips can beflushed down the toilet is at most 700 seconds in terms of the length oftime required for them to disperse in discrete lumps.

                  TABLE 7                                                         ______________________________________                                                    Composition of Surface Resin Coats                                Type of Supports                                                                            (PVP)       (Bx-1)                                              ______________________________________                                        (j-1)         100         0                                                   (j-2)         95          5                                                   (j-3)         90          10                                                  (j-4)         80          20                                                  (j-5)         70          30                                                  (j-6)         60          40                                                  (j-7)         50          50                                                  (j-8)         30          70                                                  ______________________________________                                    

                  TABLE 8                                                         ______________________________________                                        Type of Supports for Assay Strips                                                                Dispersing time (sec.)                                     ______________________________________                                        (j-1)              13                                                         (j-2)              16                                                         (j-3)              21                                                         (j-4)              35                                                         (j-5)              57                                                         (j-6)              100                                                        (j-7)              300                                                        (j-8)              undispersed                                                (B)                13                                                         ______________________________________                                    

Experiment 10

Each of the body fluid assay strips obtained in the above-mentionedexamples and comparative example was fixed at the end opposite to thereagent layer carrying end, and tilted and held at an angle of 45° withrespect to horizontal. With a syringe spaced 10 mm away from the strip,3 ml of water was sprayed onto the central region--located about 40 mmaway from the reagent layer carrying end--of the reagent layer carryingside of the strip for 2 seconds, followed by two water injections. Then,the strip was hold horizontally for 60 seconds. After that, how much thestrip was marred on the surface was observed. It was found that theuntreated control support (B) and the support (j-1) treated on thesurface with 100% polyvinyl pyrrolidone resin were both marred on thereagent layer carrying surfaces. However, the surface coats of othersupports were found to have a water resistance sufficient to stand up tothe syringe tests. Experiment 11

Two supports (j-1) and (j-1), . . . , or two supports (B) and (B) wereput on each other while their reagent layers were brought in contactwith each other. While a load of 20 g/cm² was applied over the striplaminate from above, it was allowed to stand in an atmosphere of 40° C.and 50% RH for 12 hours. After that, one strip was released from theother by a finger tip to observe whether or not blocking took place.

The results are reported in Table 9.

                  TABLE 9                                                         ______________________________________                                        Type of Supports for Assay Strips                                                                  Blocking                                                 ______________________________________                                        (j-1)                Blocking occurred                                        (j-2)                No blocking                                              (j-3)                No blocking                                              (j-4)                No blocking                                              (j-5)                No blocking                                              (j-6)                No blocking                                              (j-7)                No blocking                                              (j-8)                No blocking                                              (B)                  No blocking                                              ______________________________________                                    

Likewise, two supports (j-1) and (j-1), . . . , or two supports (B) and(B) were put on each other while the reagent layer side of one strip wasbrought in contact with the reagent layer-free side of the other. Insimilar manners as mentioned above, whether or not blocking took placewas observed. It was found that all the strips showed no sign ofblocking whatsoever.

EXAMPLE G Formation of Resin Coat on the Surface of Fibrous Material

The above-mentioned neutral paper (B) was coated on one surface witheach of the mixed resins indicated in Table 10 (to a thickness of about30 μm and a coverage of 5.0 g/m² on dry matter basis). After that, itsback surface was coated with each of the same mixed resins (to athickness of about 30 μm and a coverage of 25.0 g/m² on dry matterbasis) to obtain a body fluid assay strip support.

Coating Agent

To obtain this, a given amount of a well-stirred mixture of 15% byweight of polyvinyl pyrrolidone with 1,4-dioxane and a given amount of awell-stirred mixture of 15% by weight of polyvinyl butyral with1,4-dioxane, both mixtures obtained with the use of a homomixer, werefully mixed together by means of a spatula

Coating Manner

A 5.0-g/m² coating-drying cycle was repeated five times with a Miya barNo. 6 to obtain a coat about five times greater in thickness than thoseof Examples A-F.

In the instant example, the supports (k-1) to (k-8) for body fluid assaystrips, indicated in Table 10, were used along with a control supportformed of the aforesaid paper (B) provided on both its sides with nocoating agent. Each of the resin-coated supports was designed such thatwhen it was cut into a rectangular flat strip of 8 mm ×80 mm, a squareflat region of 5 mm ×5 mm to receive a reagent layer was left on thesurface coat in the vicinity of the strips end. A glucose assay reagentlayer composed of the following components was printed on that region bymeans of an 8-mesh screen printing plate.

    ______________________________________                                        Composition for Glucose Assay Reagent                                         ______________________________________                                        Glucose oxidase          3.6    p.b.w.                                        Peroxidase               2.4    p.b.w.                                        Guaiac fat               4.8    p.b.w.                                        Sorbitan monolaurate     7.2    p.b.w.                                        L-ascorbyl stearate      0.24   p.b.w.                                        Citric acid              2.8    p.b.w.                                        Soda citrate             11.0   p.b.w.                                        Polyvinyl pyrrolidone (Colidone 90                                                                     12.6   p.b.w.                                        made by BASF AG)                                                              Polyvinyl butyral (Eslec BX-1 made                                                                     2.25   p.b.w.                                        by Sekisui Chemical Co., Ltd.)                                                Fine cellulose powders (Abycell TG-D                                                                   171    p.b.w.                                        made by Asahi Chemical Industry,                                              Co., Ltd.)                                                                    n-Amyl alcohol           171    p.b.w.                                        Butyl Cellosolve acetate 67     p.b.w.                                        ______________________________________                                    

Each of the aforesaid supports provided with the reagent layers was cutinto rectangular flat strips of 8 mm ×80 mm, having square flat reagentlayers of 5 mm ×5 mm near their ends, thereby obtaining body fluid assaystrips embodying this invention. In similar manners, a control strip wasobtained.

Experiment 12

About 500 cc of water placed in a beaker were agitated by means of astirrer until 3 to 4-cm high, stable vortices were obtained. Then, eachof the body fluid assay strips of (8 mm ×80 mm) was put in water tomeasure the length of time (seconds) required for it to disperse indiscrete lumps.

The obtained results of the water-solubility and dispersibility tests ofthe strips are reported in Table 11.

It is understood that an index to whether or not the strips can beflushed down the toilet is not greater than 700 seconds in terms of thelength of time required for them to disperse in discrete lumps.

                  TABLE 10                                                        ______________________________________                                                   Composition of Surface Resin Coats                                 Type of Supports                                                                           (PO)         (Bx-1)                                              ______________________________________                                        (k-1)        100          0                                                   (k-2)        95           5                                                   (k-3)        90           10                                                  (k-4)        80           20                                                  (k-5)        70           30                                                  (k-6)        60           40                                                  (k-7)        50           50                                                  (k-8)        30           70                                                  ______________________________________                                    

                  TABLE 11                                                        ______________________________________                                        Type of Supports for Assay Strips                                                                Dispersing time (sec.)                                     ______________________________________                                        (k-1)              16                                                         (k-2)              25                                                         (k-3)              38                                                         (k-4)              60                                                         (k-5)              80                                                         (k-6)              280                                                        (k-7)              700                                                        (k-8)              undispersed                                                (B)                13                                                         ______________________________________                                    

Experiment 13

Each of the body fluid assay strips obtained in the above-mentionedexamples and comparative example was fixed at the end opposite to thereagent layer carrying end, and tilted and held at an angle of 45° withrespect to horizontal. With a syringe spaced 10 mm away from the strip,3 ml of water was sprayed onto the central region--located about 40 mmaway from the reagent layer carrying end--of the reagent layer carryingside of the strip for 2 seconds, followed by two water injections. Then,the strip was hold horizontally for 60 seconds. After that, how much thestrip was marred on the surface was observed. It was found that thecontrol support untreated on both its sides and the support (k-1)treated on the surface with 100% polyvinyl pyrrolidone resin were bothmarred on the reagent layer carrying surfaces. However, the surfacecoats of other supports were found to have a water resistance sufficientto stand up to the syringe tests.

Experiment 14

Two supports (k-1) and (k-1) . . . , or two supports (B) and (B) wereput on each other while their reagent layers were brought in contactwith each other. While a load of 20 g/cm² was applied over the striplaminate from above, it was allowed to stand in an atmosphere of 40° C.and 50% RH for 12 hours. After that, one strip was released from theother by a finger tip to observe whether or not blocking took place.

The results are reported in Table 12.

                  TABLE 12                                                        ______________________________________                                        Type of Supports for Assay Strips                                                                  Blocking                                                 ______________________________________                                        (k-1)                Blocking occurred                                        (k-2)                No blocking                                              (k-3)                No blocking                                              (k-4)                No blocking                                              (k-5)                No blocking                                              (k-6)                No blocking                                              (k-7)                No blocking                                              (k-8)                No blocking                                              (B)                  No blocking                                              ______________________________________                                    

Likewise, two supports (k-1) and (k-1), . . . , or two supports (B) and(B) were put on each other while the reagent layer side of one strip wasbrought in contact with the reagent layer-free side of the other. Insimilar manners as mentioned above, whether or not blocking took placewas observed. It was found that all the strips showed no sign ofblocking whatsoever.

EXAMPLE H

Using each of the mixed resins of polyethylene oxide (PO) (POLYOX WSRN-750 made by Union Carbide Co, Ltd.) with polyvinyl butyral (Bx-1)(Eslec Bx-1 made of Sekisui Chemical Co., Ltd.), the neutral paper (B)obtained from the water-dispersible and -soluble fibrous material ofExample F was coated to a coverage of 5.0 g/m² on dry matter basis toobtain a body fluid assay strip support.

Coating Agent

To obtain this, a given amount of a well-stirred mixture of 15% byweight of polyvinyl pyrrolidone with 1,4-dioxane and a given amount of awell-stirred mixture of 15% by weight of polyvinyl butyral with1,4-dioxane, both mixtures obtained with the use of a homomixer, werefully mixed together by means of a spatula.

Coating Manner

Coating was effected with a Miya bar No. 6.

                  TABLE 13                                                        ______________________________________                                                   Composition of Surface Resin Coats                                 Type of Supports                                                                           (PO)         (Bx-1)                                              ______________________________________                                        (l-1)        100          0                                                   (l-2)        95           5                                                   (l-3)        90           10                                                  (l-4)        80           20                                                  (l-5)        70           30                                                  (l-6)        60           40                                                  (l-7)        50           50                                                  (l-8)        30           70                                                  ______________________________________                                    

Using the above-mentioned supports (l-1) to (l-8) and the controlsupport made of the above-mentioned paper (B), body fluid assay stripswere obtained together with a control one in similar manners asmentioned in Example F.

Experiment 15

The results of experimentation carried out by following the proceduresof Example F are reported in Table 14.

                  TABLE 14                                                        ______________________________________                                        Type of Supports for Assay Strips                                                                Dispersing time (sec.)                                     ______________________________________                                        (l-1)              15                                                         (l-2)              20                                                         (l-3)              30                                                         (l-4)              45                                                         (l-5)              75                                                         (l-6)              150                                                        (l-7)              400                                                        (l-8)              undispersed                                                (B)                13                                                         ______________________________________                                    

Experiment 16

Experimentation was performed by following the procedures of Example F.It was found that the control support (B) untreated on both its sidesand the support (l -1) treated on the surface with 100% polyvinylpyrrolidone resin were both marred on the reagent layer carryingsurfaces. However, the surface coats of other supports were found tohave a water resistance sufficient to stand up to the syringe tests.Experiment 17

Two supports (l-1) and (l-1), . . . , or two supports (B) and (B) wereput on each other while their reagent layers were brought in contactwith each other. While a load of 20 g/cm² was applied over the striplaminate from above, it was allowed to stand in an atmosphere of 40° C.and 50% RH for 12 hours. After that, one strip was released from theother by a finger tip to observe whether or not blocking took place.

The results are reported in Table 15.

                  TABLE 15                                                        ______________________________________                                        Type of Supports for Assay Strips                                                                   Blocking                                                ______________________________________                                        (l-1)                 No blocking                                             (l-2)                 No blocking                                             (l-3)                 No blocking                                             (l-4)                 No blocking                                             (l-5)                 No blocking                                             (l-6)                 No blocking                                             (l-7)                 No blocking                                             (l-8)                 No blocking                                             (B)                   No blocking                                             ______________________________________                                    

Likewise, two supports (l-1) and (l-1), . . . , or two supports (B) and(B) were put on each other while the reagent layer side of one strip wasbrought in contact with the reagent layer-free side of the other. Insimilar manners as mentioned above, whether or not blocking took placewas observed. It was found that all the strips showed no sign ofblocking whatsoever.

EXAMPLE I Formation of Resin Coat on the Surface of Fibrous Material

Using each of the mixed resins of polyethylene oxide (PO) (POLYOX WSRN-750 made by Union Carbide Co, Ltd.) with polyvinyl butyral (Bx-1)(Eslec Bx-1 made of Sekisui Chemical Co., Ltd.), the neutral paper (B)obtained from the water-dispersible and -soluble fibrous material ofExample E was coated one surface to a thickness of about 30 μm and acoverage of 25.0 g/m² on dry matter basis. After that, the paper wascoated on the back surface with the same mixed resin to the samethickness and coverage to obtain a body fluid assay strip support.

It is noted that the coating agent and manner used for forming theabove-mentioned resin coats are:

Coating Agent

To obtain this, a given amount of a well-stirred mixture of 15% byweight of polyethylene oxide with 1,4-dioxane and a given amount of awell-stirred mixture of 15% by weight of polyvinyl butyral with1,4-dioxane, both mixtures obtained with the use of a homomixer, werefully mixed together by means of a spatula.

Coating Manner

A 5.0-g/m² coating-drying cycle was repeated five times with a Miya barNo. 6 to obtain a coat about five times greater in thickness than thoseof Examples A-F.

                  TABLE 16                                                        ______________________________________                                                   Composition of Surface Resin Coats                                 Type of Supports                                                                           (PO)         (Bx-1)                                              ______________________________________                                        (m-1)        100          0                                                   (m-2)        95           5                                                   (m-3)        90           10                                                  (m-4)        80           20                                                  (m-5)        70           30                                                  (m-6)        60           40                                                  (m-7)        50           50                                                  (m-8)        30           70                                                  ______________________________________                                    

Using the above-mentioned supports (m-1) to (m-8) and the controlsupport made of the above-mentioned paper (B), body fluid assay stripswere obtained together with a control one in similar manners asmentioned in Example F.

Experiment 18

The results of experimentation carried out by following the proceduresof Example F are reported in Table 14.

                  TABLE 17                                                        ______________________________________                                        Type of Supports for Assay Strips                                                                Dispersing time (sec.)                                     ______________________________________                                        (m-1)              16                                                         (m-2)              30                                                         (m-3)              45                                                         (m-4)              75                                                         (m-5)              110                                                        (m-6)              300                                                        (m-7)              700                                                        (m-8)              undispersed                                                (B)                13                                                         ______________________________________                                    

Experiment 19

Experimentation was performed by following the procedures of Example F.It was found that the control support (B) untreated on both its sidesand the support (m-1) treated on the surface with 100% polyvinylpyrrolidone resin were both marred on the reagent layer carryingsurfaces. However, the surface coats of other supports were found tohave a water resistance sufficient to stand up to the syringe tests.

Experiment 20

Two supports (m-1) and (m-1), . . . , or two supports (B) and (B) wereput on each other while their reagent layers were brought in contactwith each other. While a load of 20 g/cm² was applied over the striplaminate from above, it was allowed to stand in an atmosphere of 40° C.and 50% RH for 12 hours. After that, one strip was released from theother by a finger tip to observe whether or not blocking took place.

The results are reported in Table 18.

                  TABLE 18                                                        ______________________________________                                        Type of Supports for Assay Strips                                                                   Blocking                                                ______________________________________                                        (m-1)                 No blocking                                             (m-2)                 No blocking                                             (m-3)                 No blocking                                             (m-4)                 No blocking                                             (m-5)                 No blocking                                             (m-6)                 No blocking                                             (m-7)                 No blocking                                             (m-8)                 No blocking                                             (B)                   No blocking                                             ______________________________________                                    

Likewise, two supports (m-1) and (m-1), . . . , or two supports (B) and(B) were put on each other while the reagent layer side of one strip wasbrought in contact with the reagent layer-free side of the other. Insimilar manners as mentioned above, whether or not blocking took placewas observed. It was found that all the strips showed no sign ofblocking whatsoever.

The body fluid assay unit according to this invention comprises asupport including a water-soluble and -dispersible fibrous substrate anda water-soluble and dispersible resin coat formed on one surface of saidsubstrate and a body fluid assay reagent layer formed on the surface ofsaid resin coat provided on said fibrous substrate. That water-solubleand -dispersible resin coat formed on the one surface of saidwater-soluble and dispersible fibrous substrate comprises a mixed resinof 50 to 95 parts by weight of a water-soluble resin with 50 to 5 partsby weight of a polymeric water-insoluble resin, and that reagent layeris formed of a coat layer using a resin as a vehicle.

In the present body fluid assay device of such construction as mentionedabove, the support is formed by the paper-making step and the step ofapplying a coating agent to the paper. Thus, the support is easy tomanufacture. In addition, while the support possesses the rigidityrequired to serve as a body fluid assay unit support, it is so wellsoluble and dispersible in water that, after use, it can be sanitarilyand easily disposed of in toilet facilities.

In the body fluid assay device according to this invention, the assayreagent layer formed of a coat layer is provided on the surface of theresin coat on the support's surface. When forming the assay reagentlayer, it is thus unlikely that the coating agent for forming the assayreagent layer may penetrate through the support. Accordingly, this assayreagent layer is well colored.

In the body fluid assay device according to this invention, the assayreagent layer is formed of a coat layer in which the same type of resinas the resin component of the coat layer formed on the supports surfaceis used as a vehicle. Thus, increased adhesion is obtained between thesupport and the assay reagent layer.

It is noted that since the assay reagent layer on the body fluid assaydevice according to this invention is formed of a coat layer in which amixed resin of a water-soluble resin with a water-insoluble resin isused as a vehicle, a solvent having a suitable degree of dryness can beused for obtaining an assay reagent layer-forming ink composition usedwhen forming the assay reagent layer on the support. This inkcomposition has good printability, etc.

Since the support is coated with a specific resin coat, the body fluidassay unit according to this invention possesses such toughness as toenable a body fluid sample to be injected from a syringe onto thereagent layer, i.e. such toughness as to enable a sample, e.g. a urinesample to be inspected by injecting it directly onto the reagent layer,not via a vessel such as a cup. In addition, blocking is prevented fromoccurring by mixing a highly hygroscopic resin likely to be blocked,such as PVP with a water-insoluble resin.

INDUSTRIAL APPLICABILITY

The water-disintegrable material according to this invention, forinstance, may be applicable to formats for confidential papers, framesfor raising rice seedlings, seeding sheets, seedling sheets,water-soluble water absorption paper and substrates for body fluid assaydevices. Before or during use, it plays a recording medium, delivery,protection or other role while its shape is retained. After use, it canbe eventually disposed of by dissolving and dispersing it in water.

We claim:
 1. A device for assaying a body fluid comprising:a supportcomprising a water-soluble or water-dispersible fibrous substrate; awater-soluble or water-dispersible resin coat formed on at least onesurface of said substrate; and a body fluid assay reagent layer formedon said water-soluble or water-dispersible resin coat, saidwater-soluble or water-dispersible resin coat comprising a mixture of 50to 95 parts by weight of polyvinyl pyrrolidone and 50 to 5 parts byweight of polyvinyl butyral, said body fluid assay reagent layercomprising a coat layer using a resin as a vehicle, and said devicehaving sufficient rigidity to permit assaying to be readily carried outand yet capable, after assaying is carried out, of beingwater-dispersible or water-soluble to permit the device to be readilybroken up or dissolved to be flushed down a toilet.
 2. The device ofclaim 1, wherein said body fluid assay reagent layer is formed of a coatlayer using as a vehicle a mixed resin or polyvinyl pyrrolidone withpolyvinyl butyral.
 3. The device of claim 1, wherein said water-solubleor water-dispersible fibrous substrate comprises a paper comprisingfibrous carboxymethylcellulose or carboxyethylcellulose having a degreeof etherification of 0.1 to 1.0.
 4. The device of claim 3, wherein saidfibrous carboxymethylcellulose or carboxyethylcellulose has a degree ofbase saturation of at least 20% and said paper provides a solution ordispersion having a pH from 5.0 to 8.0
 5. A device for assaying a bodyfluid comprising:a support comprising a water-soluble orwater-dispersible fibrous substrate having a front surface and a backsurface; a water-soluble or water-dispersible resin coat formed on afront surface and a back surface of said substrate; and a body fluidassay reagent layer formed on said water-soluble or water-dispersibleresin coat formed on the front surface of said substrate, saidwater-soluble or water-dispersible resin coat formed on the frontsurface of said substrate comprising a mixture of 50 to 95 parts byweight of polyvinyl pyrrolidone and 50 to 5 parts by weight of polyvinylbutyral, said water-soluble or water-dispersible resin coat formed onthe back surface of said substrate comprising polyvinyl pyrrolidone or amixed resin of 100 parts by weight of less polyvinyl pyrrolidone with100 parts by weight or less of polyvinyl butyral, said body fluid assayreagent layer comprising a coat layer using a resin as a vehicle, andsaid device having sufficient rigidity to permit assaying to be readilycarried out and yet capable, after assaying is carried out, of beingwater-dispersible or water-soluble to permit the device to be readilybroken up or dissolved to be flushed down a toilet.
 6. The device ofclaim 5, wherein said body fluid assay reagent layer is formed of a coatlayer using as a vehicle a mixed resin of polyvinyl pyrrolidone withpolyvinyl butyral.
 7. The device of claim 5, wherein said water-solubleor water-dispersible fibrous substrate comprises a paper comprisingfibrous carboxymethylcellulose or carboxyethylcellulose having a degreeof etherification of 0.1 to 1.0.
 8. The device of claim 7, wherein saidfibrous carboxymethylcellulose or carboxyethylcellulose has a degree ofbase saturation of at least 20% and said paper provides a solution ordispersion having a pH from 5.0 to 8.0.